Lake Louise consensus methods for measuring the hypoxic ventilatory response.

Abstract

The hypoxic ventilatory response (HVR) is the body's first line of defense against environmental hypoxia, for example, at high altitude. In acute hypoxia, the HVR is a reflex increase in ventilation in response to decreased arterial PO2, which is rapidly sensed by arterial chemoreceptors primarily in the carotid bodies. With sustained exposure to hypoxia, the HVR changes (8). For example, after 5 to 20 minutes of hypoxia, ventilation "rolls off' relative to the acute hypoxic response and this is called hypoxic ventilatory decline (HVD). With continuous hypoxia, for example during acclimatization to high altitude, ventilation increases above the level of the acute HVR with ventilatory acclimatization to hypoxia (VAH). The different time domains of the HVR raise many questions about the physiological mechanisms of oxygen sensing and the control of breathing. They also raise many issues about experimental methods to measure the HVR and comparing results between laboratories. At the 13th International Hypoxia Symposium, John Severinghaus proposed consensus methods for measuring the HVR in humans, and the discussion continued at the 14th International Hypoxia Symposium in Lake Louise. The goal of this report is to stimulate further discussion and experiments so we can adopt a "Lake Louise Consensus for Measuring the HVR" at the 15th International Hypoxia Symposium in 2007.